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Influence of the rolling-resistance-based shape of coarse particles on the shear responses of granular mixtures

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Particuology 2020年第5期18卷 67-82页

作者： Yangui Zhu Zhihong Nie jian gong School of Civil Engineering Central South UniversityChangsha 410075China School of Hydraulic Engineering Changsha University of Science and TechnologyChangsha 410114China

Shear responses of dense granular mixtures of spherical coarse particles with the rolling resistance and spherical fine particles are studied via triaxial compression tests using the discrete element *** macroscale responses(shear strength and dilatancy)are *** the results with those in the literature indicates that granular mixtures with a rolling resistance coefficient of 0.5 have similar macroscale responses to those of gravel-shaped coarse particle *** quantify the microscale responses including the percentage contributions of contact types,partial coordination number,average particle rotation,average degree of interlocking,and local structural properties,A detailed analysis of the force-fabric anisotropy reveals the mechanisms of the variations in the shear strength with the rolling resistance coefficient and the fines *** mechanism of the variation in the shear strength with the fines content for granular mixtures with a rolling resistance coefficient of 0.5 is different from that for gravel-shaped coarse particle ***,we find that a rolling resistance linear model weakens the linear relationship between the stress ratio and the fabric anisotropy of strong and non-sliding contacts when the fines content is 30% and 40%.

关键词： Granular mixture Rolling resistance Particle shape Fines content Macroscale and microscale responses Anisotropy

Shear behaviours of cohesionless mixed soils using the DEM:The influence of coarse particle shape

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Particuology 2021年第2期19卷 151-165页

作者： Yangui Zhu jian gong Zhihong Nie School of Civil Engineering Central South UniversityChangsha 410075China

The coarse particles in mixed soils can be cobbles or gravels,with the main difference being their roundness(an indicator describing particle shape characteristics at an intermediate scale).The influence of coarse particle shape(i.e.,roundness)on the macroscopic and microscopic shear behaviours of cohesionless mixed soils with various fines contents(FCs)was investigated via the discrete element method in this *** shapes of coarse particles were formed using the rotation-invariant spherical harmonic method proposed by previous *** equation was proposed to predict the initial void ratios of samples in this study.A decrease in the roundness of coarse particles can increase the peak friction angle(FC≤40%)and critical friction angle(FC≤30%).As the roundness of coarse particles decreases,the peak dilatancy angle initially increases and then decreases(FC≤20%).Furthermore,it was found that the roundness of coarse particles hardly affects the classification of cohesionless mixed soils,as determined by probing the percentage contributions of coarse-coarse,coarse-fine,and fine-fine *** cohesionless mixed soils change from an underfilled structure to an interactive-underfilled structure at the critical state,the main forms of coarse-coarse contacts were ***,the force-fabric anisotropy mechanisms of the influences of the roundness and rolling resistance coefficient of coarse particles on the shear strengths of cohesionless mixed soils were found to be different.

关键词： Cohesionless mixed soils Particle shape Roundness Shear behaviours Discrete element method

Facile tuning of hydrogel properties by manipulating cationic-aromatic monomer sequences

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Science China Chemistry 2021年第9期64卷 1560-1568页

作者： Hailong Fan Yirong Cai jian Ping gong Institute for Chemical Reaction Design and Discovery(WPI-ICReDD) Hokkaido UniversitySapporo001-0021Japan Graduate School of Life Science Hokkaido UniversitySapporo001-0021Japan Faculty of Advanced Life Science Hokkaido UniversitySapporo001-0021Japan Global Station for Soft Matter GI-CoRE Hokkaido UniversitySapporo001-0021Japan

Copolymer hydrogels formed from cationic and aromatic monomers with identical monomer compositions but different average sequences were synthesized by free-radical copolymerization in various *** found that hydrogels with one-componentrich segments are mechanically stronger than those with adjacent-rich monomer sequences in water,while hydrogels with a rich cation-πadjacent sequence showed excellent mechanical strength and underwater adhesion in saltwater(0.7 M Na Cl).The molecular mechanisms for these behaviors are discussed in terms of polymer *** work reveals the importance of monomeric sequences in determining hydrogel properties and provides a facile approach to develop hydrogels with different properties but the same monomer composition.

关键词： free-radical polymerization monomer sequence hydrogel cation-πinteractions underwater adhesion

Two-Dimensional Invariant Tori in the Neighborhood of an Elliptic Equilibrium of Hamiltonian Systems

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Acta Mathematica Sinica,English Series 2009年第8期25卷 1363-1378页

作者： Hui LU jian gong YOU Department of Applied Mathematics Southeast University Nanjing 210018 P. R. China Department of Mathematics Nanjing University Nanjing 210093 P. R. China

In this paper, we prove that a Hamiltonian system possesses either a four-dimensional invaxiant disc or an invariant Cantor set with positive （n ＋ 2）-dimensional Lebesgue measure in the neighborhood of an elliptic equilibrium provided that its lineaxized system at the equilibrium satisfies some small divisor conditions. Both of the invariant sets are foliated by two-dimensional invaxiant tori carrying quasi-oeriodic solutions.

关键词： KAM iteration lower-dimensional tori small divisor conditions normal form

Effect of local non-convexity on the critical shear strength of granular materials determined via the discrete element method

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Particuology 2020年第5期18卷 105-112页

作者： Zhihong Nie Shunkai Liu Wei Hu jian gong School of Civil Engineering Central South UniversityChangshaHunan 410075China Hunan Province Key Laboratory of Geotechnical Engineering Stability Control and Health Monitoring Hunan University of Science and TechnologyXiangtanHunan 411201China School of Hydraulic Engineering Changsha University of Science and Technology Changsha 410114China

Multi-sphere clumps are commonly used to simulate non-spherical particles in discrete element method *** is of interest whether the degree of local non-convexity λ affects the mechanical behaviour of granular materials with the same non-convexity η.A series of discrete-element-method biaxial shear tests are conducted on rough particle packings with rη=0.075 and different λ values(ranging from 0.134 to 0.770).The microscale results show that the contact type changes with an increase in λ.However,the critical strength is independent of λ.The evaluation of the contributions of different contact types to the critical shear strength and a detailed analysis of the anisotropies help clarify the microscopic mechanisms that result in the independence of the critical shear strength from λ.

关键词： Multi-sphere clump Local non-convexity Discrete element method Biaxial shear test Contact type Critical shear strength

An Improved Result for Positive Measure Reducibility of Quasi-periodic Linear Systems

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Acta Mathematica Sinica,English Series 2006年第1期22卷 77-86页

作者： Hai Long HE jian gong YOU Department of Mathcmatics Nanjing University Nanjing 210093 P. R. China

In this paper, by the KAM method, under weaker small denominator conditions and nondegeneracy conditions, we prove a positive measure reducibility for quasi-periodic linear systems close to constant： X = （A（λ）＋ F（ψ, λ））X, ψ=ωwhere the parameter λ∈ （a, b）, w is a fixed Diophantine vector, which is a generalization of jorba ＆ Simo＇s positive measure reducibility result.

关键词： Quasi-periodic Reducibility KAM Non-degeneracy

Aggregated structures and their functionalities in hydrogels

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Aggregate

Aggregate 2021年第2期2卷 16-27页

作者： Kunpeng Cui jian Ping gong Institute for Chemical Reaction Design and Discovery(WPI-ICReDD) Hokkaido UniversitySapporoJapan Soft Matter GI-CoRE Hokkaido UniversitySapporoJapan Faculty of Advanced Life Science Hokkaido UniversitySapporoJapan

Biological soft tissues and hydrogels belong to the same category of soft and wet *** of them are composed of polymer network and a certain amount of water,and permeable to small *** tissues possess elaborated structures and exhibit outstanding *** the other hand,hydrogels are usually amorphous with poor *** recent years,various hydrogels with robust functionalities have been developed by introducing aggregated structures into the gel networks,widely extend their applications in diverse fields,such as soft actuators,biological sensors,and structural *** strategies are usually used to fabricate aggregated structure into hydrogels,including molecular self-assembling,microphase separation,crystallization,and inorganic *** aggregated structures entail the gel very different functionalities.A simple aggregated structure is able to bring multiple functionalities and a combination of mechanical performances of the *** this review,we describe the strategies used to construct aggerated structure in hydrogels and discuss about the close relation between the aggregated structure and *** also highlight the role of nonequilibrium aggregated structure in fabricating hydrogels with dynamic memorizing-forgetting behavior and point out the remaining challenges.

关键词： aggregated structure functionality hydrogel

Quantum discord in three-spin XXZ chain with three-spin interaction

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Science China(Physics,Mechanics & Astronomy) 2012年第9期55卷 1641-1645页

作者： YUE HaiDi ZHANG Yong gong jian School of Physical Science and Technology Inner Mongolia University Hohhot 010021 China Department of Physics Beijing University of Posts and Telecommunications Beijing 100876 China

Quantum discord, as a kind of measurement of quantum correlation, has received much attention since it was introduced. This paper focuses on studying quantum discord in three-spin XXZ chain with three-spin interaction. The effects of all kinds of pa- rameters on quantum discord in the ferromagnetic region J=-I are studied. The three-spin interaction may increase the value of quantum discord between two spins, while the anisotropy may decrease the value. In addition, the regrowth of quantum discord with temperature is found in the model. For zero temperature, quantum phase transition is existent.

关键词： quantum discord three-spin interaction XXZ-spin chain